Pain associated with fibromyalgia interferes with daily function, work, and social activities resulting in a decreased quality of life. People with fibromyalgia also have a significant amount fatigue and a fear of movement. People with fibromyalgia show enhanced excitability of pain neurons in the central nervous system and reduced pain inhibition. Therefore, one of the main treatments for patients with fibromyalgia must focus on pain relief to allow the person to function more independently both at home and at work. Transcutaneous electrical nerve stimulation (TENS) is used by health professionals to deliver electrical stimulation through the skin for pain control. Basic science studies, from the PIs laboratory, show that TENS activates descending pain inhibitory pathways to inhibit excitability of pain neurons. Thus, the ideal patient population for the treatment of TENS would be one in which there is enhanced central excitability and reduced inhibition; fibromyalgia is such a condition. We hypothesize that application of TENS to patients with fibromyalgia will reduce movement-related pain and reduce central excitability by restoring central inhibition, and that this decrease in pain and/or central excitability will reduce fatigue and fear of movement, thereby improving function and quality of life. We will test this hypothesis through 4 Specific Aims. Aim 1: test the effectiveness of repeated use of TENS on movement-related pain in people with fibromyalgia with random assignment to three treatments: standard care, placebo TENS and active TENS. Aim 2: test if pain reduction by TENS results in a concomitant decrease in fatigue and fear of movement, and an increase in function and quality of life. Outcome measures will include physical function by directly assessing daily activity with an accelerometer, as well as performing specific functional tasks. Aim 3: determine if active TENS alters pain processing in people with fibromyalgia and if improvement in clinical symptoms correlates with normalization of pain processing physiology. We will evaluate change in these physiologic parameters in responders versus non-responders as assessed clinically. Aim 4: determine if PROMIS is a useful outcome for fibromyalgia by comparing to the revised version of the fibromyalgia impact questionnaire (FIQ-R).